<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>狂奔的小球</title>
    <style>
        html, body {
            height: 100%;
            overflow: hidden;
        }
        #box{
            position: absolute;
            top: 100px;
            left: 100px;
            width: 150px;
            height: 150px;
            border-radius: 50%;
            background: lightcoral;
            cursor: move;
            z-index: 0;
        }
    </style>
</head>
<body>
    <div id="box"></div>
    <script src="./drag.js"> </script>
    <script>
        //原生JS 小技巧:
        //直接写box跟document.getElementById('box')是一样的效果
        let drag = new Drag(box);
    </script>
</body>
</html>
